(Invited) Slug-Flow Manufacturing of Nickel-Cobalt-Manganese-Oxide Cathode Particles for Lithium-Ion Batteries

Abstract

With expanding demands of lithium-ion batteries in portable electronic devices (e.g., smartphones, tablet PCs) and environmental-friendly vehicles (e.g., electric and/or hybrid vehicles), it is important to further improve safety, extend battery life, increase charge capacity, and reduce cost. A key missing component is effective and efficient manufacturing of complex active cathode materials at needed scales, such as nickel-cobalt-manganese (NCM) oxide microparticles with layered structures. Specifically, the material microparticle quality and uniformity have been difficult to control within the current reactors, thus extra correction procedures are needed, which risk product quality and reduce process efficiency. This study examines the innovative slug-flow continuous manufacturing process to directly produce well-controlled microparticles with advanced battery performance and accelerated scale-up, while enhancing fundamental understandings. The process utilizes a slug-flow reactor in which a multiphase mixture of liquid and gas in a tube spontaneously separates into slugs of liquid or slurry separated by slugs of gas. We have devised the milli-fluidic reactor and flow conditions so that hydrodynamically stable slugs form spontaneously immediately upon contact of the liquid and gas. Typical liquid/slurry slugs are 2-mm in length and 2-mm in diameter. In addition, we are able to selectively inject additional reactants in individual slugs to carry out the follow-on reactions. The sequential addition of the desired NCM precursors have allowed us to control the NCM radial profile in each particle. Microscopically, in a slug-flow reactor, each particle experiences the same environment with spatially uniform reaction conditions (kinetics, hydrodynamics) throughout the nucleation-growth process, leading to uniform particles with controlled composition and properties. Macroscopically, the manufacturing setup and conditions can remain the same while allowing convenient tuning of the production rate (scaling up or down). The electrochemical performance of the produced cathode particles is further enhanced by innovating coating treatment. Nonetheless, the technology/process equipment is being so developed that new battery chemistry can be easily incorporated with new future developments. Battery performance using NCM811 are tested and the results will be reported. Figure 1